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allow literal \0 - \9 in regsub if there is no matching sub-expression

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zimoch
2018-07-10 11:07:29 +02:00
parent d69c74bc8f
commit 19467bd5d5
3 changed files with 47 additions and 33 deletions
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19
doc/formats.html
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@ -564,8 +564,8 @@ in architecture specific RELEASE.Common.<em>arch</em> files.
If the regular expression is not anchored, i.e. does not start with
<code>^</code>, leading non-matching input is skipped.
A maximum of <em>width</em> bytes is matched, if specified.
If <em>precision</em> is given, it specifies the sub-expression whose match
is retuned.
If <em>precision</em> is given, it specifies the sub-expression in <code>()</code>
whose match is retuned.
Otherwise the complete match is returned.
In any case, the complete match is consumed from the input buffer.
If the expression contains a <code>/</code> it must be escaped like <code>\/</code>.
@ -586,12 +586,19 @@ as a post-processor for output.
</p>
<p>
Matches of the <em>regex</em> are replaced by the string <em>subst</em> with all
<code>&</code> or <code>\0</code> in <em>subst</em> replaced with the match itself and all
<code>\1</code> through <code>\9</code> replaced with the match of the corresponding sub-expression.
<code>&</code> in <em>subst</em> replaced with the match itself and all
<code>\1</code> through <code>\9</code> replaced with the match of the corresponding
sub-expression <span class="new"> if such a sub-expression exists.
Due to limitations of the parser, <code>\1</code> and <code>\x01</code> are the same
which makes it difficult to use literal bytes with values lower than 10 in <em>subst</em>.
Therefore <code>\0</code> aways means a literal byte (incompatible change from earlier version!)
and <code>\1</code> through <code>\9</code> mean literal bytes if they are larger than
the number of sub-expressions.
</span>
To get a literal <code>&</code> or <code>\</code> or <code>/</code> in the substitution write
<code>\&</code> or <code>\\</code> or <code>\/</code>.
There is no way to specify literal bytes with values less or equal to 9 in the
substitution!
</p>
<p>
If <em>width</em> is specified, it limits the number of characters processed.